If you just want to go from A to B you can use Google Maps (or any other map service) without problems. But if youre on an excursion or on a trip or a tour nothing compares to this atlas.
I started using the Rand McNally Atlas in 1997 for several tours (coast to coast, Rocky Mountains, East coast...) and it always served me well.
And now Im planning the next trip to the US (Im from Germany) and the 2015 version still is unbeatable - even as an app.
Peter M. Oden about Rand McNally Road Atlas, v1.2